Idaho Severe Flash Flood Warning | Effective 09/18/2026 16:21

Headline: 
Flash Flood Warning issued September 18 at 5:21PM MDT until September 18 at 8:15PM MDT by NWS Boise ID
Event: 
Flash Flood Warning
Urgency: 
Immediate
Effective: 
September 18, 2026 - 4:21pm
Expires: 
September 18, 2026 - 7:15pm
Description: 
FFWBOI The National Weather Service in Boise has issued a * Flash Flood Warning for... The Wapiti Burn Area in... Northeastern Boise County in southwestern Idaho... * Until 815 PM MDT. * At 521 PM MDT, emergency management reported thunderstorms producing heavy rain over the Wapiti Burn Area. The expected rainfall rate is 0.25 inches in 1 hour. Additional rainfall amounts up to 0.5 inches are possible in the warned area. Flash flooding is ongoing or expected to begin shortly. Excessive rainfall over the burn scar will result in debris flow. The debris flow can consist of rock, mud, vegetation and other loose materials. HAZARD...Life threatening flash flooding. Thunderstorms producing flash flooding in and around the Wapiti Burn Area. SOURCE...Emergency management reported debris on Idaho State Highway 21 between mileposts 103 and 105. IMPACT...Life threatening flash flooding of areas in and around the Wapiti Burn Area. * Some locations that will experience flash flooding include... Warm Springs Guard Station.
Instruction: 
This is a life threatening situation. Heavy rainfall will cause extensive and severe flash flooding of creeks...streams...and ditches in the Wapiti Burn Area. Severe debris flows can also be anticipated across roads. Roads and driveways may be washed away in places. If you encounter flood waters...climb to safety.
Area Description: 
Boise, ID
Forcast Office: 
NWS Boise ID
Sender: 
w-nws.webmaster@noaa.gov